Ethoxyline resin compositions and their preparation



United States Patent C1 ETHOXYLINE RESIN COMPOSITIONS AND THEIRPREPARATION No Drawing. Application March 7, 1957 Serial No. 644,447

Claims. (Cl. 154-140) This invention relates to new and useful resincompositions. More particularly the invention relates to resincompositions having desirable physical, chemical and electricalproperties, including long pot life and flexibility at elevatedtemperatures.

Epoxy, epoxide or ethoxyline resins, as they are variously called, arewell known in the art. Generally, such epoxy resins comprise a polyetherderivative of a polyhydric organic compound, said derivative containing1, 2 epoxy groups, said compound being selected from the classconsisting of polyhydric alcohols and phenols containing at least twophenolic hydroxy groups. For example, U. S. Patent 2,324,483 to Castandiscloses epoxy resin compositions comprising the reaction product ofphenols having at least two phenolic hydroxy groups and anepihalogenohydrin such as epichlorohydrin, the product having at leasttwo epoxy groups and being cured to a thermoset infusible mass by theuse of a carboxylic or polybasic' acid or acid anhydride such asphthalic anhydride. The use of organic nitrogen base or amine typematerials to cure epoxy resins is also well known as set forth, forexample, in Patent 2,444,333, such materials often giving a rapid cureat room temperature. Generally, however, the pot life of amine curedepoxy resins is comparatively short and their high temperaturecharacteristics are often poor. According to copending application,Serial No. 401,045, filed December 29, 1953,

CHa

HOG-COOK ClCH:CH-CH:

2,847,341 Patented Aug. 12, 1958 ice under high temperature producedstresses and to substantially recover therefrom upon release of thestress when the temperature is lowered.

A principal object of this invention is to provide new epoxy resincompositions which have desirable physical, chemical and electricalcharacteristics including low power factor, long pot life and theability even though rigid at ordinary temperatures of becoming rubberyand flexible at elevated temperatures.

Briefly, the invention comprises epoxy resin compositions, having ascuring agent organic titanium ester material and a lactam or mixture oflactams,-the cured resin having desirable qualities includingflexibility at high temperature and rigidity at ordinary temperatures.For each 100 parts by weight of epoxy resin, from 3 to 20 parts byweight of the lactam compound are used, and preferably 5 to 10 parts byweight, while the organic titanium ester is used in the amount of 2 to10 parts by weight, and preferably 3 to 5 parts by Weight. The epoxyresin used preferably has an epoxide equivalent of 175 to 375 and mostpreferably from 175 to 210.

The ethoxyline resins used in conjunction with my invention are, aspointed out above, well known in the art. They are described in CastanU. S. Patent Nos. 2,324,483 and 2,444,333, British Patent No. 518,057and British Patent No. 579,698. Generally, the ethoxyline resinsdescribed therein are the reaction product of an epihalogenohydrin suchas epichlorohydrin and a phenol having at least two phenolic hydroxygroups such as bis- (4-hydroxy phenyl)-2,2-propane. U. S. Patent Nos.2,494,295, 2,500,600 and 2,511,913 describe further ethoxyline resinswhich can be used in conjunction with my invention. The above patentsare hereby incorporated by reference in this application. The ethoxylineresins used herein have more than one epoxy group per molecule. They canbe prepared by reacting a polyhydroxy alcohol or phenol such ashydroquinone, resorcinol, glycerine and condensation products of phenolswith ketones, for example bis-(4-hydroxy phenyl)-2,2-propane withepichlorohydrin. The reaction of epichlorohydrin with bis-(4-hydroxyphenyl)-2,2-propane is as follows:

Alkali I L (i O CH3 H CH; 0

now abandoned and succeeded by continuation-impart application SerialNo. 691,173, filed October 21, 1957, and assigned to the same assigneeas this invention, it is proposed that an organic titanium material beused along with an amine as a curing agent to obtain a resinous masshaving desirable hardness, brittleness and toughness at elevatedtemperatures. Such materials are very useful in many applications.However, there are certain applications in which it is desirable that aresin used as an adhesive, filler, coating etc. in conjunction withother structures, such as wire arrays, laminates, etc. which expand ormove at elevated temperatures, become rubbery or flexible at suchtemperatures to prevent the disruptive high temperature forces fromtearing the structure apart. Thus, in the stator coils ofelectro-dynamic machines, the conductor bars of which are insulated witha resinous material, it is desirable that at high operating temperaturesof the order of 80 C. and above the insulating resin be rubbery andflexible so that it will conform to the expansion and warping of theconducting bar assemblies. By' this is not meant simply heat distortionof the resin which is permanent, but an ability to yield where n has anaverage value ranging from 0 to about 7. Such ethoxyline resins are soldunder the name of Epon by Shell Chemical Corporation, under the nameAraldite by the Ciba Company, as Epi-Rez by Devoe-Raynolds Company andas ERL resins by the Bakelite Company. The data given below for suchresins is representative.

The lactams useful in connection with the invention include pyrrolidone,piperidone and e-caprolactam, among others. In general, any compoundhaving the well-known lactam group and no other constituent reactivewith epoxy resins is useful. Thus, morpholone containing an oxygen atomin the ring is useful, as are compounds containing 3. a sulphur atom.Mixtures of lactams can also be used, and the term lactam, as usedherein, includes mixtures of such materials. It has been found that alactam material used alone is not an efiicacious curing agent for epoxyresins. When 15 parts by weight of e-caprolactam were added to 100 parts'by weight of Araldite .6020 and the mixture heated at 135 .C. to 150C., .no appreciable curing action had taken place after more than 72hours of .such heating.

The organic esters of titanium, which have been found useful .inconnection with the invention, correspond to the general formulaTi(OR,)4

wherein R is a radical selected from the group consisting of thesaturated and unsaturated aliphatic hydrocarbon radicals, for examplemethyl, ethyl, etc. and vinyl, alkyl, etc., aryl, aralkyl,alkaryland'cycloaliphaticradicals. Specific examples of esters of orthotitanic acids which may be employed include those substituted by methyl,:ethyl, propyl, isopropyl, 'n-butyl, isobutyl, secondary butyl,tertiarybutyl, etc. radicals, vinyl, allyl, butenyl radicals, etc.,phenyl, naphthyl, benzyl, cinnamyl and substituted phenyl or naphthyl,tolyl, xylyl .and phenylethyl radicals, various cycloaliphatic esterssuch as tetracyclohexyl. Thesecompounds may comprise, in addition, mixedesters having two or more difierent radicals of the group enumerated. Itwill be understood, of course, that mixtures of such titanates can beused and the term titanate, organic titanium estermaterial or organictitanium ester will be understood to include mixtures thereof.

When organic titanate ester was used alone :to :cure an epoxy resin, thecuring time was excessively long, thus eliminating the use of titaniumesters alone as a commercially feasible -or practical curing agent forepoxy resins. For example,'when 6 parts by weight of tetrabutyl titauateand 100 parts by weight of Araldite 6020 were heated together for 16hours at 135 C., only a slight increase in viscosity was noted.

It has been unexpectedly found, however, that when the two types ofmaterials mentioned above, namely lactams and organic titanium esters,are combined in certain proportions with epoxy resins, the latter iscured quickly in spite of the slow or incomplete cures obtained withtitanates alone or with lactams alone, and while such materials arerigid at room temperature, as would be expected, they are rubbery andflexible at high temperatures. The materials also have a pot life ofgenerally over four months at room temperature. I have found that epoxyresins having an epoxy equivalent of 175 to 375, and preferably .from175 to 210, are most useful in preparing epoxy resin compositionsaccording to this invention. Epoxy resins having an epoxide equivalentof over 375 contain so many reactive hydroxyl groups that the curingreaction is very rapid, resulting in a hard, rigid product ina'bout-one-half minute when heated at 135 C. to 150 C. The pot life ofthe present compositions lessens as the epoxy equivalent of the resinincreases.

The lactams and organic titanate curing agents can be added to the epoxyresin in any desired sequence. For example, the lactam and titaniumester can be mixed together and added to the epoxy and heated.Alternatively, the epoxy resin and organic'titanium ester can be heatedtogether and the lactam added thereto. Likewise, titanium ester and thelactam can be added together to the epoxy and then heated, or the lactamand the epoxy resin can be mixed together and heated and the titaniumester added to this mixture. The ingredients can be heated in an openvessel or under reduced pressure. In general, heating for about one hourat 135 C. :is sufficient to completely dissolve the solid ingredients.to a homogeneous mixture. Of course, no heating is required to dissolveliquids such as pyrrolidone.

The following examples are illustrative of'the practice of theinvention, all parts being by weight. Varying amounts of ingredients asshown in Table II were mixed '4' in a vacuum vessel equipped withthermometer and stirrer, the pressure being maintained at about 10 mm.of mercury. For each example shown, the ingredients shown in the firstline of the example were heated together for about one hour at 135 C. toobtain a homogeneous mixture. Then the rest of the curing agents shownwas added and the material further heated for 16 hours at 135 C. toobtain the material which was rigid at room temperature and rubbery andflexible at about C. and above. Power factor measurements were made atC. and 10 volts ,per mil using 200 mil thick discs which had been curedfor a total of 20 hours at C. before testing.

TABLE II Power Ex. Ingredlents Factor (Percent) L {100 parts Araldite6010'plus 3'parts TBT" 3 08 10 parts .e-eaprolactam 100 parts Araldite6010 plus 1 part TBT 2 2 parts TBT 1.1

. 10 .parts e-caprolactam 100 parts Araldite 6010 plus 3.parts TBT- 3 2parts TBT 1 l6. 4

10 parts e-caprolactam 100 parts Araldite 6010 I'Oparts e-eaprolactam i2 6 {lOOparts Araldite 6010 plus 5 parts TPT". NM

"""""" loparts e-caprolactam 7 100 parts Araldite 6010 plus 5 parts TBT1 6 10 parts e-caprolactaru v 100 parts Araldite 6010 8 5 parts TBT 5.510 partse-caprolactarn v 100 partsAraldite 6010 plus 3 parts 'IPT- 9 sam TBT 418 10 parts e-caprolactam 10 {100 parts Araldite 6010 plusBparts TPT 2 3 IOparts e-caprolactam 11 {100 parts Araldite' 6010 plus 5parts TOT" 1O 3 I lio t i iii di "W51 i 1 l par 5 re its 601 p us 5 par5 l5 parts e-caprolactam J NM 13 {100 parts Araldite 6010 plus 3 partsTPT 2 87 5 parts e-caprolactam 14 {100 parts Araldite 6010 plus 5 partsTPT I 6 4 10 parts 2-pyrrolidone-. i

JOOparts Araldite 6010 15 5 parts TBT 22. 0

10 parts 2-pyrrolid0ne 16 100 parts Araldite 6010 plus '3 parts TBT- 3 410 parts 2-pyrrolidone 17 {100 parts Araldite 6010 plus 5 parts TP KIM10 partsQ-pyrrolidone.

18 100 parts Araldite 6010 plus 5 parts T T 1 5 10 parts Z-pyrrolidone.

{100 parts Araldite 6010 plus 3 part-s TPT.. 12 0 '10 parts2-pyrrolidone 100 parts Araldite 6010 .plusl part TP'I.

-20 4 parts TBT NM 5 parts Z-pyrrolidone 100 parts Araldite 6010-plus 3parts TPT -21 2 parts TBT NM 5 parts 2-pyrrolid0ne 100 parts Araldite6010 plus 1 part; TBT

22 2parts TBT 6.0

5 parts Z-pyrrolidone 23 {100 parts Araldite 6010 plus 5 parts TBT 2 635????28MT -"rerr i .100 parts a ie 'pusopar s '{5 parts 2-pyrrolidoneNM 25 '{100 parts Araldite 6010 plus 5 parts TOT- 2 7 5 parts2-pyrrolidone.

25 {100 parts Araldite 6010 plus 3 parts TPT- 1 4 28 {6 parts2-pyrrolidone ar 5 re 1 e p us 30 {2 pa r ts TBT f than 5 .partsZ-pyrrolidone 32 {100 parts Araldite 6010 plus 5 parts TBT... 0 2 6"parts2-pyrr0 lid0ne 100 parts Epon 834 33 I 5parts TBT 1 7 5 partsQ-pyrrdlidone 34 {lfloparts Epon 834 plus 5 parts TBT. 0 5 fiparts2-pyrrolido11e 35 100 parts Epon834 plus 5 parts TBT. 25 10 partse-caprolactam l BT.tetrabutyltitanate; TPTtetraisopropyltitanate;TOT-tetra(2-ethy1hexyl)titanate. NM-not measured.

Example 36 To 100 parts of Araldite 6020 there was added with mixing 5parts of tertiarybutyltitanate and 'parts of e-caprolactam, the materialbeing cured for 16 hours at 135 C. with no preliminary cook to give amaterial which was rubbery and flexible at a temperature of about 135 C.The power factor measured as above was 5.5%

Example 37 To 200 parts of Araldite 6020 there was added 10 parts oftertiarybutyltitanate and 20 parts of e-caprolactam. The material washeated with stirring at 110 C. for 1.5 hours at which point the materialthickened. With further heating for 1.5 hours, the material became asoft, tack-free solid at room temperature and a viscous liquid at 110 C.Subsequent heating of this material for 16 hours at 135 C gave amaterial which was hard and rigid at room temperature and tough andflexible at temperatures above 100 C.

The epoxy resin compositions of this invention have many uses. They canbe used as potting compounds, and for molding purposes. When dissolvedin suitable wellknown solvents they can be used as impregnants forfibrous materials and adhesives or binders for laminates and for otherpurposes. They can also be used as coating materials for wires orelectrical conductors. They may be filled with the usual fillers invarying amounts to give compositions tailored to suit any particularneeds and can be prepared as B-stage resins.

While I have pointed out epoxy resin compositions containing certainpreferred amounts of lactam and organic titanium ester which are rigidat ordinary temperatures and rubbery and flexible at elevatedtemperatures, 'it will be realized that other proportions of titanateand lactam can be used if such specific characteristics are not requiredor desired.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. A composition of matter comprising the heat reaction product of (1)100 parts by weight of a complex epoxide resin having an epoxideequivalent of from 175 to 375, containing 1, 2 epoxide groups andcomprising a polyether derivative of a polyhydric organic compoundselected from a class consisting of polyhydric alcohols and phenolshaving at least two phenolic hydroxyl groups, (2) from 3 to 20 parts byweight of lactam and (3) from 2 to 10 parts by weight of organictitanium ester.

2. A composition of matter comprising the heat reaction product of (1)100 parts by weight of a complex epoxide resin having an epoxideequivalent of from 175 to 375, containing 1, 2 epoxide groups andcomprising a polyether derivative of a polyhydric organic compoundselected from the class consisting of polyhydric alcohols and phenolshaving at least two phenolic hydroxyl groups, (2) from 5 to 10 parts byweight of lactam and (3) from 3 to 5 parts by weight of organic titaniumester.

3. A laminated structure comprising laminae coated and impregnated witha composition of matter comprising the heat reaction product of (1)parts by weight of a complex epoxide resin having an epoxide equivalentof from to 375, containing 1, 2 epoxide groups and comprising apolyether derivative of a polyhydric organic compound selected from theclass consisting of polyhydric alcohols and phenols having at least twophenolic hydroxyl groups, (2) from about 3 to 20 parts by weight oflactam and (3) from about 2 to 10 parts by weight of organic titaniumester.

4. An electrical conductor coated with a composition of mattercomprising the heat reaction product of (l) 100 parts by weight of acomplex epoxide resin having an epoxide equivalent of from 175 to 375,containing 1, 2 epoxide groups and comprising a polyether derivative ofa polyhydric organic compound selected from the class consisting ofpolyhydric alcohols and phenols having at least two phenolic hydroxylgroups, (2) from 3 to 20 parts by weight of lactam and (3) from 2 to 10parts by weight of organic titanium ester.

5. The process of curing an epoxide resin having an epoxide equivalentof from 175 to 375, containing 1, 2 epoxide groups and comprising apolyether derivative of a polyhydric organic compound selected from theclass consisting of polyhydric alcohols and phenols having at least twophenolic hydroxyl groups, which comprises adding to each 100 parts byweight of said epoxide resin from 3 to 20 parts by weight of lactam andfrom 2 to 10 parts by weight of organic titanium ester and heating.

Schildknecht: 239-243 (1956).

Polymer Processes, volume X, pp.

1. A COMPOSITION OF MATTER COMPRISING THE HEAT REACTION PRODUCT OF (1) 100 PARTS BY WEIGHT OF A COMPLEX EPOXIDE RESIN HAVING AN EPOXIDE EQUIVALENT OF FROM 175 TO 375, CONTAINING 1, 2 EPOXIDE GROUPS AND COMPRISING A POLYETHER DERIVATVE OF A POLYHYDRIC ORGANIC COMPOUND SELECTED FROM A CLASS CONSISTING OF POLYHYDRIC ALCOHOLS AND PHENOLS HAVING AT LEAST TWO PHENOLIC HYDROXYL GROUPS, (2) FROM 3 TO 20 PARTS BY WEIGHT OF LACTAM AND (3) FROM 2 TO 10 PARTS BY WEIGHT OF ORGANIC TITANIUM ESTER. 